Researchers believe there could be life on Mars. Well, not on Mars, but underneath it. According to a new paper, briny water under the planet’s surface could hold enough oxygen to support aerobic Martian life. It’ll be tough to test the paper’s conclusions because Mars rover missions avoid areas where there could be water—they don’t want to accidentally taint any life there with rugged bacteria that survived the journey from earth. But the findings do suggest we may one day find out whether or not our solar system is more populated than we once thought. </p